Gyeongbu Line

The Seoul-Busan axis is Korea's main traffic corridor. In 1995, it housed 73.3% of Korea's population, and conducted 70% of the freight traffic and 66% of the passenger traffic. With both the Gyeongbu Expressway and Korail's Gyeongbu Line congested, the government saw the need to develop railways.[8] The first proposals for a second Seoul-Busan railway line originated from a study prepared between 1972 and 1974 by experts of France's SNCF and Japan Railway Technical Service (JARTS) on a request from the IBRD.[8][11] A more detailed 1978-1981 study by KAIST, focusing on the needs of freight transport, also came to the conclusion that the necessary capacity for freight transport on the existing Gyeongbu Line could best be released by separating off long-distance passenger traffic on a parallel high speed passenger railway, which was then taken up in Korea's next Five Year Plan.[8]

Following the 1997 Asian Financial Crisis, the government decided to finish the Gyeongbu High Speed Railway (Gyeongbu HSR) in two phases, and upgrade and electrify the conventional Gyeongbu Line for KTX services on the sections paralleling the parts of the high-speed line not completed in the first phase.[8][12]

Plans foresaw the development of the Gyeongbu Line into a high-capacity freight corridor after the completion of the second phase of the Gyeongbu HSR.[13] At the time of the opening of the Daegu–Busan section of the high-speed line on November 1, 2010, capacity available for freight trains on the conventional line was expected to increase by a factor of 7.7, while the capacity for passenger transport in the entire corridor increased by a factor of 3.4.[14]

The line was electrified in stages from 1974 to 2006:[10]

For KTX trains and new electric locomotives, top speed was also raised to up to 150 km/h.[10][15]

Korail launched KTX high-speed services with the opening of the first phase of the Gyeongbu HSR on April 1, 2004.[8] The Seoul–Busan travel distance was shortened to 408.5 km, the shortest travel time was 2 hours 40 minutes.[8]

All KTX services use the conventional Gyeongbu Line between Seoul and the start of the Siheung Interconnection at a junction after Geumcheon-gu Office station, until the Siheung Interconnection diverges in a tunnel towards the present start of the Gyeongbu HSR. The terminal for most Gyeongbu KTX services is Seoul station, for most Honam KTX services, Yongsan station.[8][16] In addition, some trains continue beyond Seoul station for 14.9 km along the Gyeongui Line to terminate at Haengsin station,[16] next to which KTX trains have a depot.[17] An additional stop at Yeongdeungpo station was proposed in 2004, however, the plans were dropped in face of opposition from locals living around Gwangmyeong station along the Gyeongbu HSR, who feared that Yeongdeungpo would draw away passengers from the new station and force its closing.[18] However, the November 1, 2010, timetable change made Yeongdeungpo a KTX stop, for newly introduced trains that also use the Gyeongbu Line on the entire Seoul–Daejeon section, to serve Suwon.[16][19]

From its opening, the Gyeongbu KTX service also returned to the Gyeongbu Line for two short sections crossing Daejeon and Daegu, where local disputes about the high-speed line alignment across urban areas held up construction;[20] and all the way from Daegu to Busan. Consequently, all but two of the stations of the Gyeongbu KTX service were on the conventional Gyeongbu Line: after the two stations on the high-speed line, Gwangmyeong and Cheonan-Asan, stops were at Daejeon, Dongdaegu (East Daegu), Miryang, Gupo and Busan.[8] Some Gyeongbu KTX services maintained service on this relation after the November 1, 2010, opening of the second phase of the Gyeongbu HSR, with the daily number of halts in Miryang and Gupo increased.[16] Korail met local demands by introducing additional KTX services between Seoul and Dongdaegu in June 2007, which used the conventional Gyeongbu Line between Daejeon and Dongdaegu to serve Gimcheon and Gumi.[21] However, these services were discontinued with the opening of the Gimcheon–Gumi station on the high-speed line.[21]

The section between Daegu and Samnangjin, the junction with the Gyeongjeon Line, is also used by the Gyeongjeon KTX services, which connect Seoul to Masan on the Gyeongjeon Line since December 15, 2010,[22] and will be extended to Jinju by 2012.[23] Stops along the Gyeongbu Line will be at Dongdaegu and Miryang.

Between Seoul and Cheonan, the Mugunghwa and Saemaul express trains on the Gyeongbu Line gave rail around a fifth of the modal share before the launch of KTX services. Due to the short distance and the location of the KTX station outside the city, the conventional line could retain most of its passengers, and the increase in the total modal share of rail was modest.[8] On the medium-distance relation from Seoul to Daejeon, KTX gained market share mostly at the expense of normal express services on the Gyeongbu Line, which decreased by half in the first year, while the total share of rail increased to a third.[8] On the long-distance relations from Seoul to Daegu and Busan, the total share of rail increased from around two-fifths to a market dominating three-fifths, with the bulk of that traffic taken by the KTX. For intercity passenger traffic on the conventional Gyeongbu Line, that translates to a sharp drop on the Daejeon-Daegu section (bypassed by KTX trains) and a sharp increase on the Daegu-Busan section.[8]